AUTOMATIC CONTAMINATION EVALUATOR FOR OPTICAL SURFACES

RECENT SHUTTLE FLIGHTS HAVE SHOWN THAT SIGNIFICANT TEMPORARYOR PERMANENT DEGRADATION OF OPTICAL SURFACES CAN OCCUR IN FLIGHT. SEVERAL OSMIUM-COATED SAMPLES, FLOWN ON SHUTTLE FLIGHT STS 5, EXPERIENCED A PERMANENT LOSS OF REFLECTIVITY BY FACTORS OF 2-3 IN THE VACUUM ULTRAVIOLET PORTION OF THE SPECTRUM. OTHER COATING MATERIALS AND WINDOWS CARRIED ABOARD EARLIER SHUTTLE FLIGHTS SUFFERED LESS OR EVEN NEGLIGIBLE DEGRADATION. NO INFORMATION ABOUT TEMPORARY DEGRADATION OR CONTAMINATION WAS GATHERED ON ANY STS MISSION. THIS PROJECT EXPLORES THE FEASIBILITY OF AN AUTOMATIC CONTAMINATION EVALUATOR (ACE). THE PROPOSED CONCEPT CONSISTS OF A LIGHT SOURCE, MONOCHROMATOR, SAMPLE WHEELS, AND PHOTON COUNTING READ-OUT FOR CONTINUOUSLY MONITORING AND UPDATING REFLECTIVITIES AND TRANSMITTANCES OF A VARIETY OF OPTICAL COATINGS AND WINDOWS DURING THE MISSION. THE SPECTRAL COVERAGE WOULD BE 1200-2100A. THE ACE WOULD PERMIT SCREENING OF OPTICAL MATERIALS FOR THEIR COMPATIBILITY WITH THE SHUTTLE ENVIRONMENT. IT COULD ALSO SERVE AS AN IN-FLIGHT DIAGNOSTIC RECORDING INSTRUMENT ON ANY STS MISSION EMPLOYING SENSITIVE OPTICS.